1. Field of the Invention
The present invention relates to an image forming apparatus such as a laser printer, and to an image carrier unit detachable to the image forming apparatus, and to a developer cartridge detachable to the image carrier unit.
2. Description of the Related Art
As for an image forming apparatus such as a laser printer, there have been known, for example, a color image forming apparatus having a plurality of developer cartridges for giving a toner onto a surface of a photosensitive drum in a photosensitive member cartridge, each of the developer cartridges being detachably arranged in juxtaposition (see, for example, Japanese Unexamined Patent Publication No. 2003-015378).
In the color image forming apparatus disclosed in Japanese Unexamined Patent Publication No. 2003-015378, guide grooves for receiving a developer cartridge in a fixed position corresponding to the photosensitive drum for each color, are arranged in the inner upper portion of each side plate of the frame of the photosensitive member cartridge, and fixed levers are pivotably attached thereto in order to retain each developer cartridge received along the guide grooves.
Each developer cartridge has a guide projection that is inserted into the guide groove from its upper open end.
In such color image forming apparatus, when the developer cartridge is attached to each corresponding photosensitive drum, the guide projections are inserted into the corresponding guide groove from above, and subsequently, the fixed levers are pivoted to retain the developer cartridge with the photosensitive member cartridge. On the other hand, when each developer cartridge is detached from the photosensitive member cartridge for replacement, the fixed levers for the corresponding developer cartridge to be removed, are pivoted in the reverse direction of attachment to be released, and the developer cartridge is withdrawn upwards along the guide groove.